Living in a Computer

We are living in a computer programmed reality, and the only clue we have to it is when some variable is changed, and some alteration in our reality occurs. We will have the overwhelming impression that we were reliving the present—deja vu—perhaps in precisely the same way, hearing the same words, saying the same words… I submit that these impressions are valid and significant, and I will even say this: such an impression is a clue that at some past time point, a variable was changed, reprogrammed (as it were) and that because of this an alternative world branched off. (Philip K. Dick, 1977)

Whether this is right or not, it certainly seems that we cannot be certain that we are not in a matrix(1). In 2003, British philosopher Nick Bostrom published a paper(2) proposing that the universe might in fact be a numerical computer simulation. In the paper, Bostrom concludes that at least one of the following propositions have to be true:

The human species is very likely to go extinct before reaching a “post-human” stage;

Any post-human civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof);

We are almost certainly living in a computer simulation.

The hypothesis that the universe is a digital computer was pioneered(3) by Konrad Zuse in 1967, and the term digital physics first employed by Edward Fredkin:

According to his theory of digital physics, information is more fundamental than matter and energy (…) he believes that the behavior of those bits, and thus of the entire universe, is governed by a single programming rule. (…) through ceaseless repetition—by tirelessly taking information it has just transformed and transforming it further—it has generated pervasive complexity. (Robert Wright, “Did the Universe Just Happen?”)

Many others have modelled the universe as a computer, including Stephen Wolfram, the Nobel laureate Gerard ‘t Hooft, Gregory Chaitin or Seth Lloyd. In 2012, a team of physicists at the University of Washington proposed a method to test the simulation hypothesis(4):

Presently, there is no indication that our universe is a simulation, or is fundamentally digital, but as physicists, we wish to explore signatures that could be imprinted on our universe by such a scenario. Theories can never be proven, but they can be constrained or disproved. The first step toward constraining or disproving a theory is to make predictions from it and establish its consequences. Our work is an attempt to identify signatures that are consistent with the universe being a computer simulation, (Constraints on Our Universe as a Numerical Simulation)